I got an error

[Anonymous]

I am trying to write code in Microsoft Excel VBA that controls Auto CAD. As a beginner in that subject, i started to just draw a line from visual basic in excel under Developer option

Unfortunately, i got an error message at the highlighted red color line

ACAD.ActiveDocument.ModelSpace.AddLine startPoint, endPoint

This is the code i am using

Sub access_Autocad()

Dim startPoint(0 To 2) As Double

Dim endPoint(0 To 2) As Double

Dim ACAD As AcadApplication  

Dim n As Integer  

For n = 1 To 10  

startPoint(0) = 1#

startPoint(1) = 1#

startPoint(2) = 0#

endPoint(0) = 5#

endPoint(1) = 5#

endPoint(2) = 0#

ACAD.ActiveDocument.ModelSpace.AddLine startPoint, endPoint

ZoomAll

Next

End Sub

[norman.yuan · Accepted solution]

The reason of the error is because your code does not initialize the variable ACAD to make it point to a running AutoCAD instance (your code runs inside Excel). That is, ACAD is Nothing. So, the code needs to try to find an existing running AutoCAD instance in the computer, and if not found, try to start AutoCAD. Only after a running AutoCAD instance is obtained, you can go ahead to do something with AutoCAD, in your case, draw lines.

The code would roughly look like:

Sub Access_AutoCAD()

  Dim ACAD As AutoCAD.Application

  Set ACAD=GetAutoCADInstance()

  If ACAD is Nothing Then Exit Sub

  ''Start to draw lines here

End Sub

Private Function GetAutoCADInstance() As AcadApplication

  On Error Resume Next

  Dim cad As AcadApplication

  Set cad=GetObject(, "AutoCAD.Application")

  If cad Is Nothing Then

    Set cad=CreateObject("AutoCAD.Application")

  End If

  Set GetAutoCADInstance=cad 

End Function